Column maintenance and/or replacement is a routine process in the field of mass spectrometry, typically requiring the operator to cool down the mass spectrometer and vent the high vacuum chamber to atmospheric pressure prior to decoupling the capillary column from the system. This process is time consuming, as the operator must wait for the system to cool, vent and then re-thermalize after startup before continuing productive work with the instrument. For instance, each time this process is performed on a quadrupole mass analyzer an estimated five hours of instrument time is lost. Further, this time is increased for some analytical instruments, which require ultra high vacuum pressure that can only be achieved with several hours of “bake out” at elevated temperature.
To avoid the above-noted disadvantages, many operators have installed “no vent” column changing systems. These systems typically require an additional restrictor to be installed in the column path, as well as a gas tank to protect against contamination during column maintenance. Unfortunately, the use of a “no vent” system prevents the operator from positioning the end of the capillary column immediately adjacent to the ionization source. As such, in addition to adding complexity, these “no vent” systems also have a tendency to introduce active sites in the column path, which results in reduced response to injected sample and poor linearity in calibration curves.
An alternative, albeit more risky, method of replacing the capillary column in GC-MS systems requires the operator to remove the current column and expose the vacuum chamber to a high flow of ambient air while quickly installing the new column. In addition to placing strain on the pumping system and causing oxidation of heated components, this method also risks introducing ferrule particulates and dust into the ion source and lens assembly as well as causing damage to the columns. The success of this method is strongly dependent on operator skill, experience and agility.
Another difficulty that is encountered during routine column maintenance is ensuring that the outlet end of the capillary column is positioned properly, every time the column is replaced. Proper positioning of the column requires a high level of operator skill as well as the use specialized tools. Failure to properly position the column when it is reattached may affect the reproducibility and reliability of analytical results that are obtained using the GC-MS system.
It would be beneficial to provide a method and system that overcomes at least some of the above-mentioned limitations and drawbacks of the prior art.